1. Reaper's Coast - Grog
2. Reaper's Coast - Marg
When you try to cross one of the two bridges you come across one of the trolls - Marg  or Grog . Each one of them wants you to pay them for crossing the bridge. Also, during the conversation, they will ask you to eliminate the other troll.
If you accept their offer you will have to go to the other bridge where you can find another troll. This quest can be completed in two ways.
Choice 1: Help Grog
If you met Grog first and decided to help him then, regardless of how your conversation with Marg goes, you will have to kill her. Trolls have an ability that regenerates their entire health each turn. This effect can be nullified by inflicting a certain status on them. In Marg's case, that status is being poisoned.
After the battle, you must go back to Grog and inform him that Marg is dead. He is happy and allows you to cross the bridge.
Reward: 13450 experience points + 3 guaranteed rewards + 1 from 4 that you can choose from depending on character's class + Reactive Armour ability
Choice 2: Help Marg
If you met Marg first or you changed your mind and decided to help her then you will have to kill Grog. In his case, statuses that nullify his regeneration are all connected to fire. Here, you must keep inflicting a status repeatedly if you want to stop his regeneration.
After the battle, you must go back to Marg and inform her that Grog is dead.
Reward: 13450 experience points + 3 guaranteed rewards + 1 from 4 that you can choose from depending on character's class